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improve acceptance simplifications using useless colors

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This fixes issue #418.

* spot/twa/acc.cc,
spot/twa/acc.hh (acc_cond::acc_code::useless_colors_patterns): New
method to detect patterns of colors allowing other colors to be added
or removed at will.
* spot/twaalgos/cleanacc.cc (simplify_acceptance_here): Use the above
patterns to remove some useless colors from transitions and hope that
this can help simplify the acceptance condition.
* spot/twaalgos/degen.cc (propagate_marks_vector): Use the pattern to
add more colors.
* tests/core/ltl2tgba2.test: Add the test case from issue #418.
* tests/core/ltl2dstar4.test, tests/core/satmin3.test,
tests/core/sccdot.test, tests/core/sim3.test,
tests/python/automata.ipynb, tests/python/decompose.ipynb,
tests/python/merge.py, tests/python/pdegen.py, tests/python/remfin.py,
tests/python/toparity.py, tests/python/tra2tba.py: Adjust all test
cases.
* NEWS: Mention this new feature.
This commit is contained in:
Alexandre Duret-Lutz 2020-07-28 22:09:33 +02:00
parent c341a3cabf
commit 0c4b701630
17 changed files with 412 additions and 287 deletions
Download patch file Download diff file Expand all files Collapse all files

75
spot/twa/acc.cc
View file

@ -1326,6 +1326,81 @@ namespace spot
return rescode;
}
namespace
{
static acc_cond::mark_t
gather_used_colors(const acc_cond::acc_word* pos)
{
acc_cond::mark_t res{};
auto start = pos - pos->sub.size;
do
{
switch (pos->sub.op)
{
case acc_cond::acc_op::And:
case acc_cond::acc_op::Or:
--pos;
break;
case acc_cond::acc_op::Fin:
case acc_cond::acc_op::Inf:
case acc_cond::acc_op::FinNeg:
case acc_cond::acc_op::InfNeg:
res |= pos[-1].mark;
pos -= 2;
break;
}
}
while (pos > start);
return res;
}
}
std::vector<std::pair<acc_cond::mark_t, acc_cond::mark_t>>
acc_cond::acc_code::useless_colors_patterns() const
{
// [({y₁,y₂,...,yₙ},{x₁,x₂,...,xₙ}),...]
std::vector<std::pair<acc_cond::mark_t, acc_cond::mark_t>>
patterns;
acc_cond::mark_t used_once = used_once_sets();
if (!used_once)
return patterns;
auto pos = &back();
auto end = &front();
while (pos > end)
{
switch (pos->sub.op)
{
case acc_cond::acc_op::And:
case acc_cond::acc_op::Or:
{
auto expect = pos->sub.op == acc_cond::acc_op::Or ?
acc_cond::acc_op::Inf : acc_cond::acc_op::Fin;
for (auto p = pos - 1, pe = pos - pos->sub.size;
p >= pe; p -= p->sub.size + 1)
if (p->sub.op == expect)
{
acc_cond::mark_t rem{};
for (auto q = pos - 1; q >= pe; q -= q->sub.size + 1)
if (p != q)
rem |= gather_used_colors(q);
rem &= used_once;
if (rem)
patterns.emplace_back(p[-1].mark, rem);
}
--pos;
break;
}
case acc_cond::acc_op::Fin:
case acc_cond::acc_op::Inf:
case acc_cond::acc_op::FinNeg:
case acc_cond::acc_op::InfNeg:
pos -= 2;
break;
}
}
return patterns;
}
bool
acc_cond::acc_code::is_parity_max_equiv(std::vector<int>& permut,
unsigned new_color,

14
spot/twa/acc.hh
View file

@ -1330,6 +1330,20 @@ namespace spot
/// \brief Return the set of sets appearing in the condition.
acc_cond::mark_t used_sets() const;
/// \brief Find patterns of useless colors.
///
/// If any subformula of the acceptance condition looks like
/// (Inf(y₁)&Inf(y₂)&...&Inf(yₙ)) | f(x₁,...,xₙ)
/// or (Fin(y₁)|Fin(y₂)|...|Fin(yₙ)) & f(x₁,...,xₙ)
/// then for each transition with all colors {y₁,y₂,...,yₙ} we
/// can add or remove all the xᵢ that are used only once in
/// the formula.
///
/// This method returns a vector of pairs:
/// [({y₁,y₂,...,yₙ},{x₁,x₂,...,xₙ}),...]
std::vector<std::pair<acc_cond::mark_t, acc_cond::mark_t>>
useless_colors_patterns() const;
/// \brief Return the sets that appears only once in the
/// acceptance.
///

30
spot/twaalgos/cleanacc.cc
View file

@ -617,6 +617,33 @@ namespace spot
}
return aut;
}
// If any subformula of the acceptance condition looks like
// (Inf(y₁)&Inf(y₂)&...&Inf(yₙ)) | f(x₁,...,xₙ)
// then for each transition with all colors {y₁,y₂,...,yₙ} we
// can remove all the xᵢ that are used only once in the formula.
//
// See also issue #418.
static bool
remove_useless_colors_from_edges_here(twa_graph_ptr aut)
{
// [({y₁,y₂,...,yₙ},{x₁,x₂,...,xₙ}),...]
auto patterns = aut->get_acceptance().useless_colors_patterns();
if (patterns.empty())
return false;
bool changed = false;
for (auto& e: aut->edges())
for (auto& p: patterns)
if (p.first.subset(e.acc))
if (auto nacc = e.acc - p.second; nacc != e.acc)
{
e.acc = nacc;
changed = true;
}
return changed;
}
}
@ -632,7 +659,8 @@ namespace spot
aut->set_acceptance(aut->acc().unit_propagation());
simplify_complementary_marks_here(aut);
fuse_marks_here(aut);
if (old == aut->get_acceptance())
bool changed = remove_useless_colors_from_edges_here(aut);
if (!changed && old == aut->get_acceptance())
break;
}
cleanup_acceptance_here(aut, true);

12
spot/twaalgos/degen.cc
View file

@ -1108,13 +1108,23 @@ namespace spot
else
si = new scc_info(aut);
unsigned ns = aut->num_states();
acc_cond::mark_t allm = aut->acc().all_sets();
unsigned es = aut->edge_vector().size();
auto patterns = aut->get_acceptance().useless_colors_patterns();
std::vector<acc_cond::mark_t> marks(es, acc_cond::mark_t{});
const auto& edges = aut->edge_vector();
for (unsigned e = 1; e < es; ++e)
marks[e] = edges[e].acc;
{
acc_cond::mark_t m = edges[e].acc;
// Add as many useless colors as possible.
for (auto& p: patterns)
if (p.first.subset(m))
m |= p.second;
marks[e] = m;
}
std::vector<acc_cond::mark_t> common_in(ns, allm);
std::vector<acc_cond::mark_t> common_out(ns, allm);